Mr. Harrison left his club days behind to found Charity: Water, a clean-water nonprofit

The breaking point for Scott Harrison came at the end of 2003 while he was partying in the resort town of Punta del Este in Uruguay. A nightclub promoter at the time, Mr. Harrison was there with his model girlfriend, surrounded by fireworks and magnums of Dom Perignon. But looking out at his rented megayacht, he wondered why, at age 28, he was so unhappy.

“I saw there would never be enough money, enough girls, enough status,” he recalls thinking. “My tombstone was going to read, ‘Here lies Scott Harrison, who has gotten over...